As a dielectric material for capacitors, there have been used high permittivity ceramic materials such as those consisting essentially of BaTiO.sub.3 and containing one or more secondary components such as, for example, CaTiO.sub.3, BaSnO.sub.3, CaZrO.sub.3, and SrTiO.sub.3. These dielectric ceramic materials have a dielectric constant ranging from 2000 to 15000 at room temperature, but they have a very high sintering temperature of 1300.degree. to 1400.degree. C. Sintering at such a high temperature consumes a large amount of energy, resulting in a considerable increase in the cost of sintering.
In addition, when these ceramic materials are used as a dielectric material for manufacture of monolithic ceramic capacitors, use of an expensive noble metal such as Pt and Pd as a material for internal electrodes is required. Monolithic ceramic capacitors are generally manufactured by forming green ceramic sheets, screening internal electrodes on the respective green sheets, stacking and pressing the green sheets to form monolithic bodies, and then firing the same at 1300.degree. to 1400.degree. C. Since the internal electrodes are heated up to the sintering temperature of the ceramic material, a material for internal electrodes is required not to melt, not to react with the ceramic dielectrics, or not to be oxidized even at a high temperature of 1300.degree. C. and above. However, the use of the noble metal prevents lowering the manufacturing cost of the monolithic ceramic capacitors because of the high cost of the noble metal.
To solve these problems, inventors of the present application have proposed in Japanese Patent Laying-Open No. 57-27974 to use a dielectric ceramic composition of a Pb(Mg.sub.1/3 Nb.sub.2/3)O.sub.3 -Pb(Zn.sub.1/3 Nb.sub.2/3)O.sub.3 -PbTiO.sub.3 system. This composition has a dielectric constant of 10000 and above and a low sintering temperature of 1030.degree. to 1150.degree. C. However, there is an increasing demand of development of a dielectric ceramic composition with a higher dielectric constant. In addition, it has been required to develop a dielectric ceramic composition which satisfies standards for temperature characteristics of static capacity defined under EIA standard Z5U.